Perfect example, Tim.
We've got most of the Mozart symphonies on Philips, with Haitink in the Konzertgebau. For years I described those LP's as veiled, soft, rolled off highs, little sense of soundspace, etc.
Today, while they may not quite match an audiophile label, they've gotten much closer. Low level detail, extended highs and the rich and deep acoustics of that hall are in ample evidence with multiple echoes off back/side walls and the whole bit.
Same for many DG pressings, the band behind Ella on the Verve reissues of the 'Songbooks', etc., etc. The number of bad or even mediocre LP's is much lower than supposed, at least in our collection.
Jdaniel,
I've admired your passion for and knowledge of classical music since you first joined the forum fray a few years ago. I wish I had the time to acquire your knowledge.
Regarding sonics however, I invite you to visit next time you're in the neighborhood, and perhaps expand your sense of what's possible.
If your master tape and LP of the Munch Berlioz Requiem (for example) both sound strident, that doesn't disprove or even test the hypothesis that such stridency arises from distortions in the reproduction system. 'A priori', it is impossible to know whether such problems are due to a bad recording or to the exceptional dynamics and complexity of the recording presenting too many challenges for the system(s) you've heard. In this case, I guarantee that system problems are to blame. I have that LP and it sounds magnificent. Three years ago I'd have firmly endorsed your conclusion, but I was wrong and you are too.
With respect, there is equipment which will do less damage to a signal than the pieces you listed. None of it is cheap, but it exists. Play those problematic LP's or tapes in some systems passionately and uncompromisingly built over many years to minimize distortions while maximizing dynamics - in most cases you'll be happily surprised.